This invention relates to a utility knife and more particularly to a utility knife handle for mounting a replaceable blade.
In retractable-blade utility knives, the blade is slidably movable from a sheathed position wherein the blade is enclosed in the knife handle to an extended unsheathed position wherein the knife blade projects through an opening in the knife handle to present a cutting edge. Such a utility knife is disclosed in Robinson, Jr., U.S. Pat. No. 3,107,426, entitled "Utility Knife" wherein the knife incorporates a blade carrier which mounts and supports the blade within the interior of the knife handle for selective longitudinal movement therein. The blade carrier includes a thumb actuated button to release the blade carrier from one of several latching positions for shifting the blade to another longitudinal position. The knife handle is disassembled by removal of a retaining screw to allow replacement of the blade within the carrier.
In other types of utility knives such as the fixed blade knife disclosed in the commonly assigned U.S. Pat. No. 4,524,518 to West entitled "Utility Knife", the knife holder comprises a pair of elongated mating handle members interconnected for relative pivotal movement. The pivotal movement of the handle members affords ready access to the interior of the knife holder in the open position for convenient and easy blade removal and replacement. In the closed position, the blade is securely mounted between the handle members for cutting operations.
Generally, it is desirable for a retractable utility knife to afford convenient and easy blade replacement as well as being economical to manufacture and safe in use. However, a common shortcoming in such knives is the characteristic of relatively loose blade condition when the blade is in the extended unsheathed position. That is, the mounted blade tends to exhibit a side wobble characteristic when the blade is advanced to the extended unsheathed position which can detrimentally affect the stability of the blade during cutting operations.
Accordingly, it is an object of the present invention to provide a new and improved retractable knife which alleviates blade instability and side wobble in extended unsheathed positions.
Another object of the invention is to provide such a retractable knife which affords easy and convenient blade replacement. Included in this objective is the provision of such a retractable knife with interconnected swivel case sections which afford blade replacement access without the necessity of tools or disassembly of the knife.
A further object of the invention is to provide such a retractable knife which is economical to manufacture. Included within this objective is the provision of a new and improved blade carrier for such a knife which is an integrally formed sheet metal component and economical to manufacture.
Yet another object of the invention is to provide such a retractable knife which is refined in appearance and durable in use.
Still another object of the invention is to provide a fixed blade utility knife which affords enhanced blade stability and convenient blade replacement.
Other objects will be in part obvious and in part pointed out more in detail hereinafter.
It has been found that the foregoing and related objects and advantages are attained in a knife holder which includes an elongated case having a forward blade retaining end, a rearward handle end, a blade opening in the forward end, and an interior guide for guiding a blade carrier. The blade carrier is adapted for mounting a replaceable blade and is slidably mounted to the guide of the case for selective longitudinal movement therealong between a retracted sheathed position and an extended unsheathed position wherein the forward portion of the blade mounted to the carrier extends through the blade opening to present a cutting edge. The blade carrier has a planar side portion, blade supports extending laterally from the planar side portion for supporting a blade so that one side surface of the blade faces against the planar side portion of the blade carrier, and a retaining tab assembly extending laterally from the planar side of the carrier for lateral retention of the rearward portion of the blade toward the planar side portion of the carrier. The case has an arcuate retainer at the blade opening for retaining the forward end portion of the blade toward the planar side portion of the carrier when the carrier is in an extended unsheathed position wherein the arcuate retainer coacts with the retainer tab when the blade carrier is in the unsheathed position to retain the side surface of the blade toward the planar side portion of the blade carrier to stabilize the blade during usage and ensure blade retention on the carrier.
In one embodiment, the blade carrier comprises a one piece sheet metal slide having upper and lower ends and forward and rearward ends. A web portion having a planar face for abutting the planar side surface of the blade extends between the upper and lower ends of the slide. An upper flange portion is integrally formed at the upper end of the slide so as to project laterally from the web portion with the flange being adapted to engage the upper end of the blade mounted within the slide. A lower flange portion is integrally formed at the lower end of the slide so as to project laterally from the web portion to engage the lower end of the blade mounted within the slide. The upper and lower flanges cooperate and coact to removably transversely retain the blade within the slide. A forwardly extending resilient button arm is integrally formed at the upper end of the slide and is adapted for manual actuation to selectively secure the carrier in a plurality of longitudinal positions within the case of the knife. A longitudinally extending guide rail is integrally formed on the web portion of the slide and projects outwardly therefrom intermediate the upper and lower ends of the slide. The guide rail is adapted for cooperative engagement with the guide of the case to guide the movement of the slide between the retracted sheathed position and the extended unsheathed position.